Enable synchronous texture streaming for IsaacSim RTX

[huidongc]

Description

Disable async texture streaming in the headless Kit app while keeping texture streaming itself enabled:

'rtx-transient'.resourcemanager.enableTextureStreaming = true
'rtx-transient'.resourcemanager.texturestreaming.async = false

Motivation: With async texture streaming enabled, Isaac RTX camera renders could vary across runs, which breaks golden-image / pixel-diff rendering correctness tests. Synchronous texture streaming restores stable pixel output.

Scope: apps/isaaclab.python.headless.kit only. Texture streaming remains on; only the async path is turned off.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Validation

Pixel determinism

Re-ran Isaac RTX rendering correctness tests (lift_kuka_hetero, lift_kuka_homo, shadow_hand; AOVs: rgb / rgba / albedo / simple_shading_diffuse_mdl / simple_shading_full_mdl) 20 times after this change.

• All cases: 0.00% PixelDiff vs golden on every run (N=20, std=0)
• Actual images were byte-identical across runs (same SHA256)

This confirms the setting restores deterministic Isaac RTX render output for these tests.

Performance / memory impact

Dexsuite runtime benchmark on Isaac-Lift-KukaAllegro-Camera (newton_mjwarp + isaacsim_rtx, seed 42, 1000 measured iterations) before (develop / 62e1433e) vs after (this change).

Variant	Envs	FPS Δ%	Env create Δ%	First step Δ%	GPU mem peak Δ%	RAM peak Δ%
homogeneous	1024	−2.98%	+2.99%	+0.03%	+2.54%	−0.12%
homogeneous	2048	+1.04%	−0.52%	+1.24%	−1.11%	+0.43%
homogeneous	4096	+0.33%	+1.54%	+1.25%	−2.31%	−0.09%
homogeneous	8192	−0.95%	−1.65%	−6.06%	−1.51%	+0.06%
heterogeneous	1024	−0.77%	+1.74%	+3.77%	−4.58%	+0.12%
heterogeneous	2048	−0.59%	+1.35%	+3.51%	−3.38%	+0.64%
heterogeneous	4096	+0.31%	−0.12%	+0.61%	−1.97%	+0.09%
heterogeneous	8192	+1.48%	+0.70%	+2.70%	−1.01%	+0.13%

Δ% = (after − before) / before × 100. Sign meaning by metric:

Metric	+ means	− means	Prefer
FPS	after is faster	after is slower	higher (+)
Env create / First step	after takes longer	after is quicker	lower (−)
GPU / RAM mem peak	after uses more memory	after uses less memory	lower (−)

Takeaways:

• FPS impact is within run-to-run noise (~±3%; confirmed by repeating noisy develop outliers).
• GPU memory peak is slightly lower in most configs (~1–5%).
• Host RAM and env-creation time are essentially unchanged.

Machine:

CPU: AMD Ryzen Threadripper PRO 5975WX (32 cores / 64 threads)
GPU: NVIDIA RTX A6000.
RAM: 251 GB (~251.5 GiB)
OS: Ubuntu 22.04

Checklist

• I have read and understood the contribution guidelines
• I have run the pre-commit checks with ./isaaclab.sh --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have added a changelog fragment under source/<pkg>/changelog.d/ for every touched package (do not edit CHANGELOG.rst or bump extension.toml — CI handles that)
• I have added my name to the CONTRIBUTORS.md or my name already exists there

[isaaclab-review-bot]

Isaac Lab Review Bot

The PR adds one headless Kit default that keeps texture streaming enabled while selecting its synchronous path. The setting is colocated with the existing texture-streaming and asynchronous-rendering controls, and no actionable defect is evidenced by the patch.

• Design and architecture: The change is scoped to apps/isaaclab.python.headless.kit and aligns the texture resource manager with the headless application's existing synchronous-rendering defaults. Other Kit application configurations remain unchanged, which is a deliberate scope boundary rather than a demonstrated defect.
• API: No public Python API, CLI argument, symbol, or configuration dataclass changes. The behavioral compatibility surface is limited to the headless Kit default; texture streaming remains enabled, while its scheduling changes from asynchronous to synchronous.
• Implementation: The new rtx-transient.resourcemanager.texturestreaming.async setting is placed directly beside the existing texture-streaming enablement and follows the surrounding Kit/TOML syntax. The main non-blocking tradeoff is potentially different texture load-time behavior in the headless application.

No blocking issues. No inline issue met the actionable-evidence threshold; the assessment above records the review feedback.

Automated review; human maintainers own approval decisions.

[greptile-apps]

Greptile Summary

The PR configures the default headless IsaacLab experience to retain texture streaming while disabling its asynchronous mode.

• Adds the synchronous texture-streaming setting to the base headless Kit configuration.
• The setting is inherited by the headless rendering experience.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
apps/isaaclab.python.headless.kit	Adds a single Kit setting that disables asynchronous texture streaming for standard headless launch paths.

_{Reviews (2): Last reviewed commit: "Disable async texture streaming" | Re-trigger Greptile}

[nvsekkin]

question: there are also golden image comparison tests in source/isaaclab_visualizers/test/golden_images/* those test passed without update https://github.com/isaac-sim/IsaacLab/actions/runs/31102324567/job/92630269455

strangely, the updated goldens failed validation: https://github.com/isaac-sim/IsaacLab/actions/runs/31102324567/job/92630269451#step:4:528

[huidongc]

question: there are also golden image comparison tests in source/isaaclab_visualizers/test/golden_images/* those test passed without update https://github.com/isaac-sim/IsaacLab/actions/runs/31102324567/job/92630269455

The scope of the PR will only affect sensor renders using Kit RTX. The visualizer part is not touched.

[huidongc]

Synchronous texture streaming determinism fix landed on Kit 110.3.0-356733 , but we pin Isaac Sim 6.1.0-alpha.38  which is using Kit  110.3.0-351613 .

My MR is now blocked until the Isaac Sim issue is fixed and we pin newer Isaac Sim and thus newer Kit.